The energy we receive from the Sun in the form of light and heat is called Solar Energy. As it is well known that solar energy is the renewable, cleanest, and most abundant form of energy available on the planet. In various applications such as electricity generation, heating, transportation, and more, solar energy is considered most sustainable form of energy, as sun provides more energy than humanity consumes on daily basis. Today, we are using solar energy in small-scale applications such as calculators to large utility-scale power plants to produce clean electricity. Solar energy is becoming popular because the world is working on reducing greenhouse gas emissions and dependency on fossil fuels.
What is Solar Energy?
The form of radiant energy produced by the Sun is referred to as Solar Energy. The solar energy provided by the Sun travels approximately 150 million kms through the space to reach on the Earth. In this journey, it takes about 8 minutes and 20 seconds.
On the Earth, we have arrangements to convert and utilize the solar energy into the following forms of energy –
- Electricity
- Heat
- Mechanical energy
- Chemical energy
In this tutorial, we will focus our discussion on conversion of solar energy into electricity. For this, we have a technology called Solar Photovoltaic (PV) System. Solar PV System can directly convert solar energy into electricity.
Solar Energy Definition
In the context of electrical engineering, solar energy is the form of renewable energy which is obtained from the Sun’s radiation and converted into electrical energy using solar photovoltaic systems.
It is termed as Renewable Energy (RE) because the Sun is continuously producing energy and it is virtually inexhaustible on a human timescale. In other words, we say solar energy is naturally replenished itself. As per scientific observations, it is expected that the Sun will continuously produce energy for approximately next 5 billion years.
How Does Solar Energy Work?
The conversion of solar energy into electricity is a four-step process as given below –
- Step 1: Production of Solar Energy in The Sun – Inside the sun, nuclear fusion of hydrogen atoms takes place and results in production of large amount of energy. This energy comes out of the Sun in the form of electromagnetic radiation.
- Step 2: Solar Energy Reaches the Earth – Solar energy in the form of electromagnetic radiation passes through the space and Earth’s atmosphere, where some part of it gets reflected and absorbed by clouds and gases. The remaining part reaches the Earth’s surface.
- Step 3: Solar PV Panels Capture Solar Energy – Solar photovoltaic panels are installed to capture the solar energy from sunlight received on the Earth.
- Step 4: Generation of Electricity – Solar PV panels absorb energy of photons of sunlight and produce DC electricity. This DC electricity is converted into AC electricity for further utilization.
Common Types of Solar Energy Systems
Depending on the solar energy capturing technology, there are following three major types of solar energy systems –
- Solar Photovoltaic System – Solar PV system is the most common type of solar energy system used to produce electricity from sunlight. In this system, silicon-based solar photovoltaic cells are used to convert sunlight into electricity.
- Solar Thermal Energy System – Solar thermal systems are used to produce heat from sunlight and then the heat is used to produce electricity from steam.
- Concentrated Solar Power (CSP) System – In this solar energy system, mirrors are used to focus sunlight onto a receiver to produce heat, which is then used to produce steam. This heat further drives a turbine connected to a generator to generate electricity.
Main Components of Solar PV System
A typical solar photovoltaic system consists of the following key components –
Solar Panels
Solar panels are semiconductor-based electronic devices that convert solar energy into direct current electricity.
Solar Inverters
Solar inverters are power electronic devices that convert DC electricity generated by solar panels into AC electricity.
Module Mounting Structure (MMS)
MMS is the mechanical structure that supports and positions solar panels in a desired orientation and at tilt angle.
DC & AC Cables
In solar PV system, DC and AC cables are used to carry electricity among various parts of the system.
Protection Devices
Electrical protection devices such as DC isolators, AC circuit breakers, earthing system, surge protection device, etc. are used in the solar PV system to protect it from faults.
Electrical Transformers
Electrical transformers are generally used in utility-scale solar PV systems to step up the voltage levels. In a typical large solar PV system, there are two main types of transformers used, which are as –
- Inverter Duty Transformer (IDT)
- Power Transformer (PTR)
SCADA System
Supervisory Control and Data Acquisition (SCADA) System in solar PV systems is used for monitoring the plant operation and performance in real-time.
Advantages of Solar Energy
Solar energy has numerous benefits over conventional energy systems for generating electricity. Some key benefits of solar energy are listed below –
- It is the cleanest energy, as it produces electricity without causing environmental pollution.
- It is a renewable energy, and available in abundance, also replenishes itself every day.
- Solar energy offers low operating and maintenance costs, once installed.
- Electricity produced by solar energy is relatively cheaper.
- Solar energy creates energy independence.
- Solar energy reduces water consumption for generating electricity.
- Solar energy systems are easy to scale in a wide range, from few kW to several GW.
- Modern solar energy systems have longer service life of around 25-30 years.
Disadvantages of Solar Energy
Apart from advantages, solar energy systems also have several limitations and key of them are listed here –
- Solar energy is weather dependent and becomes ineffective during cloudy or rainy weather.
- Solar energy is not available at night, hence no electricity at night.
- Solar energy systems require very high initial costs, specifically for land and equipment.
What is a Solar Power Plant?
A solar power plant is a large setup designed to generate electricity from sunlight. It supplies the electricity generated to the electrical grid.
Modern utility-scale solar plants can have capacity ranging from a few megawatts (MW) to several gigawatts (GW).
A typical solar power plant consists of the following major components –
- Solar modules/panels
- String combiner boxes (SCBs)
- String or central solar inverters
- Inverter-duty and power transformers
- Switchyard & pooling substation (PSS)
- SCADA systems
- Meteorological/weather stations
- Power plant controller (PPC)